The invention relates generally to fan drive systems and more specifically to a fan penetration feature for in-vehicle testing.
In-vehicle testing of fans and fan drives is highly desirable to optimize the cooling performance of the fan on cooling system components, such as a radiator, balanced against other performance factors such a fuel economy and power usage.
In order to obtain optimal performance for an associated fan drive and clutch system, it is desirable to alter the fan penetration within the radiator shroud during in-vehicle testing. Fan penetration, for the purposes of the present invention, is defined as the distance between the fan blades and the radiator. The greater the fan penetration, the smaller the distance between the fan leading edge of the blades and the radiator, and the deeper the fan blades are positioned within a radiator shroud and away from the fan clutch assembly. As the fan is rotated at a fixed rotational speed during in-vehicle testing, fan penetration directly affects the cooling performance characteristics of the fan by changing its proximity to the radiator.
Typically, fan penetration alteration during in-vehicle testing cycles is accomplished utilizing shims placed between the fan clutch assembly and the fan to alter the relative distance between the fan and fan clutch assembly. In order to install, or alter, the location of the shims, it is currently necessary to first cool the engine from operating temperatures prior to allowing technicians to alter fan penetration. The engine must then be warmed back up to operating temperatures to conduct the test at the next fan penetration. This process in time consuming, typically taking up to two or three hours to complete each shim alteration.
Another undesirable feature associated with the use of shims to alter fan penetration is the limited amount of fan locations achievable. Typical shims allow fan position changes of about one-quarter of an inch. Thus, fan optimization can be compromised within these parameters.
It is thus highly desirable to provide a new method for performing fan penetration alterations for in-vehicle testing that address these problems.